JP2000251305A - Optical pickup and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the improvement in the frequency characteristics of an electric system and the dealing with a two-layered disk by setting the sizes of respective photodetecting regions to small sizes. SOLUTION: This optical pickup is constituted to have a hologram element 8 which is constituted with the regions divided into four regions by two straight lines of a tangential direction T and radial direction R of an optical disk 6 as a first hologram pair region 9a and a second hologram pair region 9b of the same constitution and a photodetecting substrate 2 which has the first and second photodetecting regions 10 and 11 for receiving ±1st order diffracted light from the first hologram pair region 9a and third and fourth photodetecting regions 12 and 13 for receiving the ±1st order diffracted light from the second hologram pair region 9b, arranged with the respective centers of the first to fourth photodetecting regions 10 to 13 and the converging point O of the reflected light 20 in positions optically equidistant from the center of the hologram element 8 and is trisected in the respective photodetecting regions 10 to 13 to the central division region Ea and the end division regions Eb and Ec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup and an optical disk apparatus used for reproducing an information recording medium such as an optical disk, and more particularly to a DVD (Digital V).
ersatileDisc) and CD (Compact)
Disc) compatible playback system.

[0002]

2. Description of the Related Art In recent years, CDs, which are already widely used consumer optical disk systems, have recently been replaced by higher density D optical disks.
A VD system has been proposed, commercialized, and spread. In a DVD player, which is this playback device (optical disc device), compatible playback of CDs is indispensable in order to avoid duplication of devices and complexity in use, and to play discs of these two standards. The technology has been developed, and furthermore, the simplification of the configuration for realizing the technology and the cost reduction have been issues.

[0003] In the compatible reproduction technology of CD / DVD, which of the tracking system and the focus system is appropriate will be described. With respect to the tracking method, the so-called "three-beam method" has become the mainstream in the CD system, but if this three-beam method is adopted in the DVD system, the beam position suitable for two types of disks having different track pitches can be set. This is disadvantageous in that it is difficult to generate an offset due to reflected light from a non-readout layer in a two-layer DVD disc. Therefore, CD / DV
D compatible playback uses the “DPD method” (Differenti
1 Phase Detection (phase difference method) has become mainstream.

The following points are taken into consideration for the focus method. In other words, in response to demands for cost reduction and miniaturization, attempts have been made to integrate optical pickup optical systems, and semiconductor lasers, photodetectors, and holographic devices (HOEs: Holographic Ops) have been developed.
devices have been developed and are applied to DVDs as well as CDs. In this type of optical device, it is easy to dispose a semiconductor laser and a photodetector in a close position, and to dispose the diffracted light by the hologram element and the emission point of the semiconductor laser in a substantially conjugate position. Complementary “SSD Method” (Spot Size De) Using Both ± 1st Order Diffraction Lights
(focus; spot size method) can be realized. Compared with the “knife edge method” which has been put to practical use, this focus method does not necessarily require strict position adjustment of the hologram element, does not need to discard one of the ± 1st-order diffracted lights, and has high efficiency. It has such advantages. Therefore, in the integration of the optical system, the “SSD method” (spot size method) is preferable.

The present applicant has previously proposed an optical pickup which employs tracking error detection by a phase difference method and focus error detection by a spot size method, and enables integration of an optical pickup optical system ( (See Japanese Patent Application No. 10-96365).

FIG. 12 is a schematic perspective view of the optical pickup, FIG. 13 is a plan view of a hologram element, FIG. 14 is a plan view of a light receiving element substrate, FIG. 15 is a view showing a divided area of a spot light, and FIG. It is a figure showing the irradiation state of a field. 12 to 16, a laser beam from a laser light source (not shown) is applied to an information recording layer (not shown) of the optical disc 50.
And is reflected here. A hologram element 51 and a light receiving element substrate 52 are arranged on the optical path of the reflected light.

The hologram element 51 has a substantially optical axis C of the reflected light.
And hologram areas 51a and 51b divided into two areas by using a line passing through the optical disc 50 in a direction perpendicular to the radial direction R (tangential direction T) as a boundary line. These two hologram areas 51a and 51b are:
Each is composed of the same curve group that generates the same continuous wavefront diffracted light, and the diffracted angles of the reflected light are both diffracted at the same angle, but the diffracted directions of the reflected light are diffracted in different directions. It is configured to add a lens effect of converging to one of the diffracted lights and diverging to the other.

The light receiving element substrate 52 has four first to fourth light receiving areas 53 arranged on the same plane light receiving surface 52a.
And the center of each of the four light receiving areas 53 to 56 and the convergence point O of the reflected light from the optical disk 50 are arranged at positions that are all optically equidistant from the center of the hologram element 51. I have.

The four light receiving regions 53 to 56 are irradiated with diffracted light from the hologram regions 51a and 51b, respectively, and the converged diffracted light is applied to the light receiving surface 52a.
And the diffracted light subjected to the divergent action forms a focal point or a focal line behind the light receiving surface 52a. The ± 1st-order diffracted lights have defocuses in directions opposite to each other, and have a predetermined (substantially the same) spot size.
3 to 56, and the size of the optical disk 50 also changes in the opposite direction in accordance with the positional shift of the optical disk 50 in the focus direction.

Further, as shown in detail in FIG. 16, a first light receiving area 53 and a second light receiving area 54, and a third light receiving area 55 and a fourth light receiving area 56, which are opposed to each other with the optical axis C interposed therebetween, respectively. Are defined as boundary directions + Rα and −Rα, and are divided into four along the boundary directions + Rα and −Rα. In other words, the light receiving regions 53 to 56 are separated by the center boundary portion 57, which is a non-light receiving region, and the outer boundary lines 58, 59 on the outer and inner sides, respectively. It is divided into four inside and outside end divided regions Ec and Ed.

Next, the error detecting means of the optical disk device will be described. As shown in FIG.
When the spot light 60 applied to the light-receiving area 53 is divided into four areas, the light of each of the I to IV areas is applied to the light receiving areas 53 to 56 at the positions indicated by the Roman numerals in FIG. Then, as shown in FIG. 17, the photoelectric conversion signal Ri1 from the inner side central divided region Ea and the end portion divided region Ec of the first light receiving region 53, and the inner side central divided region Ea and the second light receiving region 54 of the second light receiving region 54. The output I signal obtained by adding the photoelectric conversion signal Ri2 from the end divided region Ec and the photoelectric conversion signal Ro1 from the center divided region Eb and the end divided region Ed on the outer side of the first light receiving region 53 and the second I signal are output. Light receiving area 5
4 is a center divided region Eb and an end divided region E on the outer side.
The output IV signal is obtained by adding the photoelectric conversion signal Ro2 from d. Also, the photoelectric conversion signal Li1 from the inner side central divided region Ea and the end portion divided region Ec of the third light receiving region 55, and the photoelectric conversion signal Li1 from the inner side central divided region Ea and the end portion divided region Ec of the fourth light receiving region 56 are obtained. Photoelectric conversion signal Li
2 and the output III signal, and the photoelectric conversion signal Lo1 from the outer side center divided region Eb and the end portion divided region Ed of the third light receiving region 55 and the outer side center divided region of the fourth light receiving region 56. The output II signal is obtained by adding Eb and the photoelectric conversion signal Lo2 from the end portion divided area Ed. Then, a tracking error signal is generated by the phase difference method based on the output I to output IV signals.

Also, as shown in FIG.
3 and a pair of end divided regions Ec and E of the second light receiving region 54.
and the output Ra signal by adding the photoelectric conversion signal R2 from the pair d to the pair of end divided regions Ec and Ed of the first light receiving region 53.
And the photoelectric conversion signal R4 from the pair of central divided areas Ea and Eb of the second light receiving area 54 are added to obtain an output Rb signal. Also, the third light receiving area 5
5 and a pair of end divided regions Ec and E of the fourth light receiving region 56.
and the output La signal obtained by adding the photoelectric conversion signal L2 from the pair d to the pair of end divided regions Ec and Ed of the third light receiving region 55.
And the photoelectric conversion signal L4 from the pair of central divided areas Ea and Eb of the fourth light receiving area 54 are added to obtain an output Lb signal. Then, based on the difference level between the output Ra signal and the output Rb signal and the difference level between the output La signal and the output Lb signal, a focus error signal is generated by a two-system complementary (complementary) spot size method. Is configured.

That is, in the above prior art, the optical disk 5
The reflected luminous flux from 0 is divided into two in the radial direction by the hologram element 51 and divided into two in the tangential direction by the respective light receiving areas 53 to 56 of the light receiving element substrate 52. Splitting is realized, and a double complementary (complementary) spot size method is realized by using all the ± 1st-order diffracted lights of the two-divided hologram element 51.

[0014]

However, in the above prior art, each light receiving area 53 to 56 must be divided into four parts, so that the overall size becomes large. Specifically, as shown in FIG. 6B, the four divided areas E
The minimum width possible in the manufacturing process of a to Ed is W ₁ , and the minimum width possible in the manufacturing process of each of the three boundary lines 57, 58, 59 is W
_If it is set to ₂ , the size width becomes 4W ₁ + 3W ₂ , and the size becomes large.

Here, the DVD system has a higher transfer rate than the CD system, and the frequency characteristic of the electrical system is C
About 6 times the D ratio is required. In the light receiving regions 53 to 56 serving as signal sources of the electric system, since the capacitance (C) proportional to the area is one of the factors that influence the frequency characteristics, the smaller the light receiving area is, the better. But,
In the prior art, as described above, the light receiving regions 53 to 56
Cannot be set small, so that the frequency characteristics cannot be improved.

In the DVD system, there is a standard for a two-layer disc. This two-layer disc has two signal surfaces arranged at intervals of several tens of μm by bonding, and the lower layer is made of a transflective film. In the reproduction of this two-layer disc, the light spot is focused on one of the layers, but the light spot is reflected in an unfocused state by the other one layer as well.
The light is greatly spread on the light receiving element substrate 52 and irradiated. Since the irradiated light component may be mixed with the detection signal to cause an offset, the adverse effect is reduced as the light receiving area is reduced. However, in the above-described prior art, the size of the light receiving areas 53 to 56 cannot be set small as described above, so that there is a possibility that it is not possible to cope with a two-layer disc.

Accordingly, the present invention has been made to solve the above-mentioned problem, and the tracking error detection by the phase difference method and the focus error detection by the spot size method are performed by setting the size of each light receiving area to be small. It is an object of the present invention to provide an optical pickup, an optical device, and an optical disk device capable of improving the frequency characteristics of an electric system and adapting to a dual-layer disk.

[0018]

According to a first aspect of the present invention, there is provided an optical pickup for irradiating an information recording medium with light and reading information by using the reflected light from the information recording medium. And is divided into at least four areas by two straight lines, a direction substantially parallel to the track of the information recording medium, passing through the optical axis of the reflected light, and a direction substantially orthogonal to the track. Are formed as a first hologram pair region combining two portions of the same hologram curve group and a second hologram pair region different from the first hologram curve group and combining two portions of the same hologram curve group. The first hologram pair region and the second hologram pair region diffract each of the reflected lights in different directions, and converge or diverge for each of the diffracted lights. And configured hologram element so as to add the first and second light receiving regions for receiving ± 1 order diffracted lights respectively from the first hologram pair region of the hologram element, ± from the second hologram pair region
An optical pickup comprising: a light receiving element substrate having third and fourth light receiving regions for receiving the first-order diffracted light, respectively, on the same plane.

According to a second aspect of the present invention, in the optical pickup according to the first aspect, the light receiving element substrate has a center of each of the first to fourth light receiving areas and a convergence point of light reflected from the information recording medium. Are positioned at optically substantially equal distances from the center of the hologram element, and the first light receiving area, the second light receiving area, and the third light receiving area, which are opposed to each other with the optical axis interposed therebetween. A light is characterized in that a direction connecting the centers of the region and the fourth light receiving region is defined as a boundary direction, and the light is divided into three along the boundary direction into a central divided region and both outer end divided regions. It is a pickup.

According to a third aspect of the present invention, there is provided an optical disc apparatus for irradiating light onto an information recording medium and reading information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, Are divided into at least four areas by two straight lines, a direction substantially parallel to a track of the information recording medium and a direction substantially orthogonal to the track of the information recording medium. A first hologram pair region combining two parts of the same hologram curve group,
In contrast to this, the second hologram pair region is formed by combining two portions of the same hologram curve group, and
The hologram pair region and the second hologram pair region are configured to diffract the respective diffracted lights of the reflected light in directions different from each other, and to add a convergent or divergent lens function to each diffracted light, respectively. A hologram element and ± 1 from the first hologram pair area of the hologram element.
First and second light receiving areas for receiving the second order diffracted light, respectively;
Third and fourth light receiving areas for receiving ± 1st-order diffracted light from the second hologram pair area, respectively, on the same plane;
Each of the centers of the first to fourth light receiving areas and the convergence point of the reflected light from the information recording medium are arranged at positions where they are all optically equidistant from the center of the hologram element,
A direction in which the centers of the first light receiving region and the second light receiving region, and the third light receiving region and the fourth light receiving region, which are opposed to each other with the optical axis interposed therebetween, is defined as a boundary direction. The light receiving element substrate is divided into three parts along the central divided area and the end divided areas on both sides thereof, and the photoelectric conversion from the central divided area of the first to fourth light receiving areas of the light receiving element substrate The difference level between the signal and the added value of the photoelectric conversion signals from the end light receiving areas on both sides is obtained, and a focus error signal of a so-called spot size method is obtained based on the difference level, and the first light receiving area and the second light receiving area are obtained. , And all the photoelectric conversion signals from the third light receiving area and the fourth light receiving area are added. From the outputs of these two systems, the tracking error of the so-called two-element phase difference method is obtained. An optical disk apparatus characterized by comprising an error signal detecting means for obtaining a over signal simultaneously.

According to a fourth aspect of the present invention, there is provided an optical disc apparatus for irradiating an information recording medium with light and reading information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, Are divided into at least four areas by two straight lines, a direction substantially parallel to a track of the information recording medium and a direction substantially orthogonal to the track of the information recording medium. A first hologram pair region combining two parts of the same hologram curve group,
In contrast to this, the second hologram pair region is formed by combining two portions of the same hologram curve group, and
The hologram pair region and the second hologram pair region are configured to diffract the respective diffracted lights of the reflected light in directions different from each other, and to add a convergent or divergent lens function to each diffracted light, respectively. A hologram element and ± 1 from the first hologram pair area of the hologram element.
First and second light receiving areas for receiving the second order diffracted light, respectively;
Third and fourth light receiving areas for receiving ± 1st-order diffracted light from the second hologram pair area, respectively, on the same plane;
Each of the centers of the first to fourth light receiving areas and the convergence point of the reflected light from the information recording medium are arranged at positions where they are all optically equidistant from the center of the hologram element,
A direction in which the centers of the first light receiving region and the second light receiving region, and the third light receiving region and the fourth light receiving region, which are opposed to each other with the optical axis interposed therebetween, is defined as a boundary direction. The light receiving element substrate is divided into three parts along the central divided area and the end divided areas on both sides thereof, and the photoelectric conversion from the central divided area of the first to fourth light receiving areas of the light receiving element substrate The difference level between the signal and the added value of the photoelectric conversion signals from both outer end light receiving areas is obtained. Based on the difference level, a focus error signal of a so-called spot size method is obtained, and the first light receiving area and the second light receiving area are obtained. The photoelectric conversion signals from the end divided regions corresponding to the respective regions are added to obtain outputs of two systems, and the photoelectric conversion signals from the corresponding end divided regions of the third light receiving region and the fourth light receiving region are obtained. Each To obtain two outputs by these 4
An optical disc device comprising: an error signal detecting means for simultaneously obtaining a so-called four-element phase difference tracking error signal from a system output.

According to a fifth aspect of the present invention, there is provided an optical disc apparatus for irradiating light to an information recording medium and reading information by using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, Are divided into at least four areas by two straight lines, a direction substantially parallel to a track of the information recording medium and a direction substantially orthogonal to the track of the information recording medium. A first hologram pair region combining two parts of the same hologram curve group,
In contrast to this, the second hologram pair region is formed by combining two portions of the same hologram curve group, and
The hologram pair region and the second hologram pair region are configured to diffract the respective diffracted lights of the reflected light in directions different from each other, and to add a convergent or divergent lens function to each diffracted light, respectively. A hologram element and ± 1 from the first hologram pair area of the hologram element.
First and second light receiving areas for receiving the second order diffracted light, respectively;
Third and fourth light receiving areas for receiving ± 1st-order diffracted light from the second hologram pair area, respectively, on the same plane;
Each of the centers of the first to fourth light receiving areas and the convergence point of the reflected light from the information recording medium are arranged at positions where they are all optically equidistant from the center of the hologram element,
A direction in which the centers of the first light receiving region and the second light receiving region, and the third light receiving region and the fourth light receiving region, which are opposed to each other with the optical axis interposed therebetween, is defined as a boundary direction. The light receiving element substrate is divided into three parts along the central divided area and the end divided areas on both sides thereof, and the photoelectric conversion from the central divided area of the first to fourth light receiving areas of the light receiving element substrate The difference level between the signal and the added value of the photoelectric conversion signals from both outer end light receiving areas is obtained. Based on the difference level, a focus error signal of a so-called spot size method is obtained, and the first light receiving area and the second light receiving area are obtained. The photoelectric conversion signals from the end divided regions corresponding to the regions are respectively added, and the photoelectric conversion signals from the central divided regions of the first light receiving region and the second light receiving region are further added to the respective added values. Add System outputs, add the photoelectric conversion signals from the corresponding end divided areas of the third light-receiving area and the fourth light-receiving area, and add the third light-receiving area and the Error signal detecting means for obtaining the outputs of two systems by further adding the respective photoelectric conversion signals from the central divided region with the four light receiving regions, and simultaneously obtaining a so-called four-element phase difference tracking error signal from the outputs of these four systems. An optical disk device comprising:

According to another aspect of the present invention, there is provided an optical disc apparatus that irradiates an information recording medium with light and reads information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, The information recording medium is divided into at least four areas by two straight lines passing through the optical axis of the reflected light and substantially in the tracking direction of the information recording medium and in the direction substantially orthogonal to the information recording medium. A first hologram pair region in which two portions of the hologram curve group are combined, and a second hologram pair region in which two portions of the different and the same hologram curve group are combined,
The first hologram pair region and the second hologram pair region diffract each reflected light of the reflected light in different directions,
A hologram element configured to add a convergent or divergent lens function to each diffracted light, and a first hologram element that receives ± first-order diffracted lights from the first hologram pair region of the hologram element, respectively. And a second light receiving area, and third and fourth light receiving areas for respectively receiving ± 1st-order diffracted light from the second hologram pair area on the same plane. The first light receiving area is disposed at a position where the convergence point of the reflected light from the information recording medium and the center of the hologram element are all optically substantially equidistant from each other, and is opposed to the optical axis. A direction in which the centers of the third light receiving region and the fourth light receiving region are connected to each other is defined as a boundary direction. A center divided region and end divided regions on both sides of the central divided region along the boundary direction. And to A light receiving element substrate divided into three, a photoelectric conversion signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate, and an added value of the photoelectric conversion signals from the end light receiving areas on both sides. The difference level is taken, and a focus error signal of a so-called spot size method is obtained based on the difference level, and the photoelectric conversion signals from the corresponding end divided regions of the first light receiving region and the second light receiving region are added, respectively. Two systems of outputs are obtained, and the photoelectric conversion signals from the corresponding end divided regions of the third light receiving region and the fourth light receiving region are respectively added to obtain two systems of outputs. One system is obtained by adding the photoelectric conversion signals from the respective central divided regions of the light receiving region, and one system is obtained by adding the photoelectric conversion signals from the respective central divided regions of the third light receiving region and the fourth light receiving region. And get the output of Further comprising an error signal detecting means for obtaining a tracking error signal simultaneously from the output of the six systems is an optical disk apparatus according to claim.

According to the present invention, by using a delay circuit or the like, it is possible to satisfactorily avoid the occurrence of an offset to the tracking error signal due to the movement of the objective lens, which is difficult to avoid by the so-called two-element phase method.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view of an optical pickup of an optical disk device according to a first embodiment of the present invention, FIG. 2 is a perspective view of a main part of the optical pickup, and FIG. FIG. 3B is a diagram showing four regions of a cross section between the optical disk 6 and the hologram 8, FIG. 3B is a plan view of the hologram element 8, FIG.
FIG. 5 is a main part plan view showing four light receiving areas 10 to 13 and spot lights SP1 to SP4 applied to the light receiving areas 10 to 13.

1 to 5, a light receiving element substrate 2 is fixed on a wiring board 1, and the structure of the light receiving element substrate 2 will be described later. A laser light source 3 and a micro mirror 4 are fixed on the light receiving element substrate 2 in a straight line. The laser light source 3 is composed of, for example, a semiconductor laser, and is fixed via a submount member 5 fixed on the light receiving element substrate 2. The micro mirror 4 has a surface facing the laser light source 3 configured as a mirror surface (particularly, without a reference numeral), and the mirror surface is configured as a surface inclined at 45 degrees with respect to a horizontal plane.

That is, the emitted light from the laser light source 3 is reflected by the micromirror 4 to be converted into light having a vertical optical axis C, and passes through the vertical optical axis C to be transmitted to the information recording medium. It is configured such that light emitted to a certain optical disk 6 and reflected from the optical disk 6 returns through the same optical axis C.

On the optical axis C in the vertical direction, an objective lens 7 and a hologram element 8 are arranged in this order from the optical disk 6 side. The objective lens 7 converges light guided from the laser light source 3 via the hologram element 8 to an information recording layer (not shown) of the optical disc 6.

The hologram element 8 has a partial square shape,
It has a circular hologram component 8a on its upper surface. The hologram forming unit 8a passes through the optical axis C of the reflected light 20 and has a substantially tangential direction (direction parallel to the track) T of the optical disk 6 and a substantially perpendicular direction R
It is divided into four areas SI, SII, SIII and SIV by two straight lines orthogonal to (almost in the radial direction of the optical disc 6). Regions SII and SIV arranged diagonally to these four regions are the first region.
As the hologram pair region 9a, regions SI and SIII arranged at other diagonals are each configured as a second hologram pair region 9b.

The first hologram pair region 9a and the second hologram pair region 9b are formed by combining two portions of the same hologram curve group that generates diffracted light beams having the same continuous wavefront, respectively. Are diffracted at the same diffraction angle, but the diffracted light of the reflected light 20 is diffracted in different diffraction directions, and one of the paired ± first-order diffracted lights 21a, 21b, 22a, and 22b is It is configured to add convergence and divergence lens action to the other.

Here, the first hologram pair area 9a and the second hologram pair 9a
Since the light is diffracted at the same diffraction angle in the hologram pair region 9b, the spot lights SP1 to SP4 on the four light receiving element substrates 2
SP4 is irradiated to a position equidistant with respect to a point orthogonal to the optical axis C on the light receiving element substrate 2, and the first hologram pair region 9a
± 1st-order diffracted lights 21a and 21b and the ± 1st-order diffracted lights 22a and 22b by the second hologram pair region 9b are diffracted in different diffraction directions, so that four spot lights S
P1 to SP4 are irradiated on the light receiving element substrate 2 at positions rotated by ± α degrees with respect to the radial direction R.

The light receiving element substrate 2 has four light receiving areas 10 to 13 arranged on the same plane light receiving surface 2a.
The first to fourth light receiving regions 10 to 13 are configured to be irradiated with the four diffracted lights 21a, 21b, 22a, and 22b, respectively. Also, the first to fourth light receiving areas 10 to 10
Reference numeral 13 denotes a position where each of the centers and the convergence point O of the reflected light 20 from the optical disk 6 are optically substantially equidistant from the center of the hologram element 8. A first light receiving region 10 and a second light receiving region 11, which are opposed to each other with the optical axis C interposed therebetween;
The direction connecting the centers of the third light receiving region 12 and the fourth light receiving region 13 is defined as a boundary direction + Rα, −Rα, and along the boundary direction + Rα, −Rα, the central divided region Ea and both outer sides thereof are arranged. 3 for each of the end divided regions Eb and Ec
Has been split. This division ratio is such that the center division area Ea and the two end division areas E
The spot light amounts of b and Ec are set to be the same. In addition, as shown in FIG. 6A, the three divisions are, specifically, two boundary portions 17, 1 which are non-light receiving portions.
8 is used.

The light receiving element substrate 2 and the laser light source 3 are integrally fixed to the same wiring substrate 1 and further sealed with the hologram element 8 to form an integrated optical device 19. Further, the optical pickup is incorporated in the housing 14 in combination with the objective lens 7 to constitute an optical pickup. 1 and 2, the wiring substrate 1 and the hologram element are illustrated as being separated for convenience. However, in practice, the hologram element 8 is placed on the wiring substrate 1,
The light receiving element substrate 2 and the laser light source 3 are sealed. Next, the error detecting means 15 of the optical disk device will be described. As shown in FIGS. 7 and 8, the error detecting means 15 converts the photoelectric conversion output R1 from the output from the central divided area Ea of the first light receiving area 10 into a pair of end divided areas Eb, Eb, From the total output from Ec, the photoelectric conversion output R
3 are obtained. Central divided area E of second light receiving area 11
a from the output from the second light receiving area 1
A photoelectric conversion output R2 is obtained from the total output from one pair of end divided regions Eb and Ec. Also, the third light receiving area 1
2 from the output from the central divided area Ea
Is divided into a pair of end divided areas Eb and Ec of the third light receiving area 12.
The photoelectric conversion output L3 is obtained from the total output from.
The photoelectric conversion output L4 is obtained from the output from the central divided area Ea of the fourth light receiving area 13, and the photoelectric conversion output L2 is obtained from the total output from the pair of end divided areas Eb and Ec of the fourth light receiving area 13. _{Then, FE 1 = (R1 + R2} ) - (R
3 + R4) and FE ₂ = (L1 + L2) − (L3 +
L4).

That is, the + 1st-order diffracted lights 21a and 21b diffracted by the hologram element 8 are focused before the light receiving element substrate 2, and the -1st order diffracted lights 22a and 22b are focused after passing the light receiving element substrate 2, When focused, both spot lights SP1 to SP4 have the same size. Then, as described above, in the just-focused state, the light receiving amount of the central divided region Ea of each of the light receiving regions 10 to 13 and the total light receiving amount of the pair of end divided regions Eb and Ec are set to be the same amount. Therefore, the value of FE _{1 and} the value of FE ₂ are both zero. When the focus is not focused, the + 1st-order diffracted light 21a, 21b or -1
Order diffracted light 22a, 22b one is large, because the other is small, the value of the FE _1, the value of the FE ₂ becomes a value shifted from zero, FE _1, FE ₂ by two systems of complementary (complementary) focus An error signal can be obtained.

As shown in FIG. 8, the error detecting means 15 converts the photoelectric conversion signals from the central divided area Ea of the first light receiving area 10 and the end divided areas Eb and Ec on both sides into the second light receiving area. 11 and output by adding the photoelectric conversion signals from the center divided area Ea and the outer edge divided areas Eb and Ec.
Get II + IV signal. Also, the photoelectric conversion signals from the center divided region Ea and the outer end divided regions Eb and Ec of the third light receiving region 12 and the center divided region Ea and both outer end divided regions Eb and Eb of the fourth light receiving region 13 are provided. The output I + III signal is obtained by adding the photoelectric conversion signal from Ec. Then, based on the output (II + IV) signal and the output (I + III) signal, DP
The D operation circuit 16 is configured to generate a tracking error signal by the phase difference method.

Next, the operation of the above configuration will be described. When laser light is emitted from the laser light source 3, the emitted light is reflected by the micromirror 4 and changed to light having an optical axis C in the vertical direction. After passing through the hologram element 8, the light having the optical axis C is usually collimated by a collimator lens (not shown), and focused on an information recording layer (not shown) of the optical disk 6 by the objective lens 7. . The reflected light from the optical disk 6 is incident on the hologram element 8 again while converging along the reverse path.

Here, the light that has passed through the hologram element 8 as the 0th-order diffracted light converges to a convergence point O, and the optical distance to the convergence point O is set to be substantially equal to the optical distance to each of the light receiving regions 10 to 13. Therefore, when it is assumed that the hologram element 8 has no lens power, each diffracted light has a relationship converging on each of the light receiving regions 10 to 13. FIG.
As shown in (a), the spot light 23 on the optical disc 6
Is divided into four regions, the light in each of the I to IV regions is irradiated to the position indicated by the Roman numeral in FIG.

Accordingly, before one of the ± first-order diffracted lights 21a and 21b by the first hologram pair region 9a reaches the light receiving surface 2a due to the lens power, a focal point or a focal line is formed, and the other of the ± first-order diffracted lights 21a and 21b. Makes a focal point or a focal line behind the light receiving surface 2a by the lens power. And ±
Spot lights SP1, SP2 of the first-order diffracted lights 21a, 21b
Are defocused in opposite directions to each other, are radiated to the first and second light receiving areas 10 and 11 with a predetermined (substantially the same) spot size, and the size of the optical disc 6 also changes in the opposite direction due to a positional shift in the focus direction. Will do. Further, the spot lights SP1 and SP2 of the ± 1st-order diffracted lights 21a and 21b by the first hologram pair area 9a have components of the II area and the IV area of the spot light 23 shown in FIG.

The second hologram pair area 9b
One of the first-order diffracted lights 22a and 22b is focused or focused before reaching the light receiving surface 2a by the lens power, and the other of the ± first-order diffracted lights 22a and 22b is focused or focused backward from the light receiving surface 2a by the lens power. Connect the lines. And ± 1
The spot lights SP3 and SP4 of the next-order diffracted lights 22a and 22b have defocuses in opposite directions, and are radiated to the third and fourth light receiving areas 12 and 13 with a predetermined (substantially the same) spot size. The size also changes in the opposite direction with the displacement. The spot lights SP3 and SP4 of the ± 1st-order diffracted lights 22a and 22b by the second hologram pair region 9b are the spot lights 2 shown in FIG.
It has three I region and III region components.

That is, spot light SP1, SP2, SP3, and SP3 whose sizes change in the opposite direction in accordance with the positional shift of the optical disk 6 in the focus direction are provided in the respective light receiving regions 10 to 13.
4 are illuminated, respectively, and as shown in FIG. 7, by adding each photoelectric conversion signal to obtain each output R2, R3, L2, L3 signal, FE ₁ = (R1 + R2)
− (R3 + R4) and FE ₂ = (L1 + L2) −
Complementary (complementary) of two lines of (L3 + L4)
Focus error can be detected by a simple spot size method. In addition, since the light receiving areas 10 to 13 are respectively irradiated with the four-diagonal components of the spot light 23 shown in FIG. 3A, as shown in FIG. By obtaining the output II + IV signal and the output I + III signal respectively, the tracking error can be detected by the two-phase difference method based on the output (II + IV) signal and the output (I + III) signal.

That is, in the present invention, the reflected light beam from the optical disk 6 is split into four light beams required by the phase difference method in the hologram element 8, and each split light beam is divided into four light beams required by the phase difference method. A phase difference method is realized by including an angular component, and a double complementary (complementary) spot size method is realized by using all the ± 1st-order diffracted lights of the 4-division hologram element 8.

Each of the light receiving areas 10 to 13 is shown in FIG.
As shown in detail in (a), it is constituted by three divisions of a center division region Ea and both outer end division regions Eb and Ec, and the minimum width which is possible in the manufacturing process of each division region Ea, Eb and Ec the W _1, when the process on the smallest possible width manufacture of each of the boundary lines 17 and 18 and W _2, the overall width is 3W ₁ + 2W _2. Therefore, in the prior art, as shown in FIG. 6B, the size width is 4W ₁ + 3W ₂ , so that it can be set smaller by the size width of W ₁ + W ₂ . As a result, the frequency characteristics of the electric system can be improved, and the reproduction of the double-layer disc can be performed well.

Further, since each of the light receiving areas 10 to 13 is constituted by three divisions, the number of wiring patterns drawn out from each of the light receiving areas 10 to 13 can be reduced as compared with the prior art, and the wiring pattern can be simplified. This contributes to simplification of the circuit and the like.

Further, as in the prior art, the laser light source 3
The optical axis C from the optical disk 6 to the optical disk 6 and the optical axis C from the optical disk 6 to the light receiving element substrate 2 are shared, and the four ± 1st-order diffracted lights 21a, 21b,
Since the light receiving elements 22a and 22b can be received by the single light receiving element substrate 2, this contributes to the integration of the optical system. Therefore, the optical device 19 in which the optical system of the optical pickup is integrated can be configured as a compact device.

In the first embodiment, in order to produce a tracking error signal by the phase difference method, an output (II + IV) signal and an output (I + II)
I) Since only two systems for signals are required, the number of output pins of the wiring board 1 is reduced as compared with the prior art, which contributes to downsizing of the wiring board 1 and eventually the optical pickup and the optical device 19.

Next, a second embodiment of the present invention will be described.
The second embodiment is different from the first embodiment only in the configuration of the tracking error detection of the error detection means 15 and the other configurations are the same. Only the configuration for error detection will be described.

That is, as shown in FIG.
0 and the photoelectric conversion signal from the inner side end divided region Eb of the second light receiving region 11 and the inner side end divided region Eb of the second light receiving region 11.
To obtain an output IV signal. The output II signal is obtained by adding the photoelectric conversion signal from the outer side end divided region Ec of the first light receiving region 10 and the photoelectric conversion signal from the outer side end divided region Ec of the second light receiving region 11. .

The photoelectric conversion signal from the inner side end divided area Eb of the third light receiving area 12 and the fourth light receiving area 13
And the photoelectric conversion signal from the inner-side end portion divided area Eb is added to obtain an output I signal. The photoelectric conversion signal from the outer side end portion divided region Ec of the third light receiving region 12 and the fourth
The output III signal is obtained by adding the photoelectric conversion signal from the outer side end divided region Ec of the light receiving region 13. And
Based on the output signals I to IV, the DPD operation circuit 16
It is configured to generate a tracking error signal by a system phase difference method.

According to the second embodiment, the photoelectric conversion signal of each central divided area Ea is not used. Each central divided area E
In a, the dividing directions + Rα, -Rα of the respective light receiving areas 10 to 13 are shown.
And the division direction R of the spot light 23, the crosstalk component of another area is mixed.
Since the photoelectric conversion signal of “a” is not used, a tracking error signal having no error due to the crosstalk component can be created.

Next, a third embodiment of the present invention will be described.
The third embodiment is different from the first embodiment only in the configuration of the tracking error detection of the error detecting means 15 and the other configurations are the same. Only the configuration for error detection will be described.

That is, as shown in FIG. 10, the inner side of the first light receiving region 10 (the inner side is the side closer to the line indicating the radial direction R on the light receiving element substrate 2, and the side farther from the outer side). The same applies to the following.) The photoelectric conversion signal from the end divided region Eb and the photoelectric conversion signals from the inner end divided region Eb and the central divided region Ea of the second light receiving region 11 are added. To obtain an output IV signal. The photoelectric conversion signal from the outer side end divided region Ec and the center divided region Ea of the first light receiving region 10 and the photoelectric conversion signal from the outer side end divided region Ec of the second light receiving region 11 are added. Obtain the output II signal.

Further, the photoelectric conversion signal from the inner side end divided area Eb of the third light receiving area 12 and the fourth light receiving area 13
Of the inner side end divided region Eb and the central divided region Ea
To obtain an output I signal. The photoelectric conversion signals from the outer side end divided region Ec and the central divided region Ea of the third light receiving region 12 and the fourth light receiving region 1
3 to obtain an output III signal by adding the photoelectric conversion signal from the outer side end divided area Ec. And this output I
The DPD arithmetic circuit 16 is configured to create a tracking error signal by a four-system phase difference method based on the signals IV to IV.

According to the third embodiment, since the photoelectric conversion signal of each central divided area Ea is added to each of the outputs I to IV, the output level is improved as compared with the second embodiment.

Next, a fourth embodiment of the present invention will be described.
The fourth embodiment differs from the first embodiment only in the configuration of the tracking error detection of the error detecting means 15 and other configurations are the same. Only the configuration for error detection will be described.

That is, as shown in FIG. 11, the photoelectric conversion signal from the inner side end divided region Eb of the first light receiving region 10 and the inner side end divided region Eb of the second light receiving region 11 are formed.
The output IV signal is obtained by adding the photoelectric conversion signal from b.
The output II is obtained by adding the photoelectric conversion signal from the outer side end divided region Ec of the first light receiving region 10 and the photoelectric conversion signal from the outer side end divided region Ec of the second light receiving region 11.
Get the signal.

The photoelectric conversion signal from the inner side end divided area Eb of the third light receiving area 12 and the fourth light receiving area 13
And the photoelectric conversion signal from the inner-side end portion divided area Eb is added to obtain an output I signal. The photoelectric conversion signal from the outer side end portion divided region Ec of the third light receiving region 12 and the fourth
The output III signal is obtained by adding the photoelectric conversion signal from the outer side end divided region Ec of the light receiving region 13.

Further, the center divided area E of the first light receiving area 10
a is added to the photoelectric conversion signal from the central divided area Ea of the second light receiving area 11, and the output RF1 signal is added to the photoelectric conversion signal from the central divided area Ea of the third light receiving area 12 and the fourth signal. The output RF2 signal is obtained by adding the photoelectric conversion signal from the central divided region Ea of the light receiving region 13 and the output. Then, based on the output I-IV signals, the output RF1 signal and the output RF2 signal, the DPD operation circuit 16
It is configured to generate a tracking error signal by a system phase difference method.

According to the fourth embodiment, the output signals I to IV do not include the photoelectric conversion signal of each central divided area Ea. In each central divided region Ea, the division directions + Rα and −Rα of the light receiving regions 10 to 13 and the division direction R of the spot light 23 are set.
However, since the crosstalk component of the other region is mixed due to the difference between the two, the photoelectric conversion signal of each center divided region Ea is not used, so that it is possible to create a tracking error signal having no error due to the crosstalk component. Also, by using a delay circuit or the like, it is possible to satisfactorily avoid the occurrence of an offset to the tracking error signal due to the movement of the objective lens, which is difficult to avoid by the so-called two-element phase difference method.

According to each of the above embodiments, the hologram element 8 is divided into four regions. However, if the reflected light amount can be obtained for the diagonally arranged regions, the hologram element 8 is divided into five or more regions. Is also good.

According to each of the above embodiments, the light receiving element substrate 2 and the laser light source 3 are integrally fixed to the same wiring substrate 1 and further sealed with the hologram element 8 to form an integrated optical device 19. However, these components may be configured separately.

According to each of the above embodiments, the laser light source 3 is fixed to the light receiving element substrate 2 via the sub-mount member 5, and the conjugate point (convergence point) of the light emission point of the laser light source 3 on the optical axis C. Although the configuration is such that the point O) is located, the laser light source 3 may be configured separately from the optical device 19. That is,
The light emitting point of the laser light source 3 or a conjugate point thereof may not be located on the optical axis C. However, fixing the laser light source 3 to the light receiving element substrate 2 as in the above embodiments contributes to the integration of the optical system.

According to each of the above embodiments, the laser light source 3 is fixed on the light receiving element substrate 2 via the submount member 5, but the conjugate point of the light emitting point of the laser light source 3 is The laser light source 3 may be directly fixed to the light receiving element substrate 2 as long as it can be located near the light receiving surface 2a. With this configuration, the number of components can be further reduced and the thickness can be reduced.

[0064]

As described above, according to the first aspect of the present invention, there is provided an optical pickup for irradiating an information recording medium with light and reading information using reflected light from the information recording medium. And at least four straight lines, a direction substantially passing through the optical axis of the reflected light and a direction substantially parallel to the track of the information recording medium and a direction substantially orthogonal to the track.
The four holograms are divided into regions, and the four diagonally arranged regions are referred to as a first hologram pair region obtained by combining two portions of the same hologram curve group, and two hologram curve groups different from the first hologram curve group. The first hologram pair region and the second hologram pair region
A hologram element configured such that the hologram pair region diffracts each of the reflected lights in different directions, and adds a convergent or divergent lens function to each of the diffracted lights; First and second light receiving regions for respectively receiving ± 1st-order diffracted light from the first hologram pair region of the element, and third and fourth light-receiving regions for receiving ± 1st-order diffracted light from the second hologram pair region, respectively.
Since a light receiving element substrate having a light receiving area and a light receiving area on the same plane is provided, the ± 1st-order diffracted light from the first hologram pair area of the hologram element becomes diagonal when the spot light applied to the information recording medium is divided into four parts. ± 1st-order diffracted light from the second hologram pair region of the hologram element is divided into four spot light beams applied to the information recording medium, and is divided in the diagonal direction. Since the four ± 1st-order diffracted lights are applied to the respective light-receiving areas of the light-receiving element substrate, the ± 1st-order diffracted lights need to be divided at the respective light-receiving areas at the center. To obtain a tracking error signal by the phase difference method and a focus error signal by the spot size method,
The division is sufficient, and the size of each light receiving area can be set small. As a result, the frequency characteristics of the electric system can be improved, and the reproduction of the two-layer disc can be performed well.

According to a second aspect of the present invention, in the optical pickup according to the first aspect, the light receiving element substrate is
Each of the centers of the first to fourth light receiving areas and the convergence point of the reflected light from the information recording medium are arranged at positions where they are all optically equidistant from the center of the hologram element,
A direction connecting the centers of the first light receiving region and the second light receiving region, and the third light receiving region and the fourth light receiving region, which are opposed to each other with the optical axis interposed therebetween, is defined as a boundary direction. Since each of the light receiving regions is irradiated with the diagonal component of the spot light because the central divided region and the outer end divided regions are respectively divided into three, the tracking error signal and the spot size method by the phase difference method are applied. , And the number of divisions of each light receiving region is three, so that the size of each light receiving region can be set small, and as a result, the frequency characteristics of the electric system can be improved, Also, the reproduction of the double-layer disc is performed well.

According to a third aspect of the present invention, in the optical disk device having the optical pickup according to the second aspect, the photoelectric conversion signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate is transmitted to both the optical pickup apparatus and the optical pickup. The difference level between the sum of the photoelectric conversion signals from the outer end light receiving area and the focus error signal of the so-called spot size method is obtained based on the difference level, and the difference between the first light receiving area and the second light receiving area is obtained. All the photoelectric conversion signals are added, and all the photoelectric conversion signals from the third light receiving region and the fourth light receiving region are added. From the outputs of these two systems, a so-called two-element phase difference tracking error signal is obtained. Since an error signal detecting means which is obtained at the same time is provided, it is possible to perform focus error detection by a so-called spot size method and tracking error detection by a so-called two-element phase difference method. It can be. In addition, since only two systems of tracking error signals are required, the number of output pins is reduced as compared with the prior art, and this contributes to, for example, miniaturization of a wiring board, and furthermore, an optical pickup and an optical device.

According to a fourth aspect of the present invention, there is provided the optical disk apparatus having the optical pickup according to the second aspect, wherein the photoelectric conversion signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate is transmitted to both of the optical pickup device. The difference level between the sum of the photoelectric conversion signals from the outer end light receiving area and the focus error signal of the so-called spot size method is obtained based on the difference level, and the difference between the first light receiving area and the second light receiving area is obtained. The photoelectric conversion signals from the corresponding end divided areas are respectively added to obtain outputs of two systems, and the photoelectric conversion signals from the corresponding end divided areas of the third light receiving area and the fourth light receiving area are respectively added. And error signal detecting means for simultaneously obtaining a so-called four-element phase difference tracking error signal from these four outputs. It can be performed modulo the focus error detection and a so-called four-element phase difference method and a tracking error detection. Further, as compared with the invention of claim 5, since a photoelectric conversion signal of each central divided area is not used, a tracking error signal having no error due to a crosstalk component can be created.

According to a fifth aspect of the present invention, there is provided the optical disk device having the optical pickup according to the second aspect, wherein the photoelectric conversion signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate is transmitted to both of the optical pickup apparatus. The difference level between the sum of the photoelectric conversion signals from the outer end light receiving area and the focus error signal of the so-called spot size method is obtained based on the difference level, and the difference between the first light receiving area and the second light receiving area is obtained. The photoelectric conversion signals from the corresponding end divided regions are added, respectively,
Further, the photoelectric conversion signals from the respective central divided regions of the first light receiving region and the second light receiving region are further added to the respective added values to obtain two-system outputs, and the third light receiving region and the fourth light receiving region are output.
The photoelectric conversion signals from the end divided regions corresponding to the light receiving region are added, and the photoelectric conversion signals from the central divided region of the third light receiving region and the fourth light receiving region are added to the respective added values. Further, an error signal detecting means for obtaining outputs of two systems by addition and obtaining a tracking error signal of a so-called four-element phase difference method from the outputs of the four systems at the same time is provided. It is possible to perform tracking error detection by a so-called four-element phase difference method. Further, since the photoelectric conversion signal of each central divided area is added to each output signal as compared with the invention of claim 4, the output level is improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an optical pickup of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of an optical pickup of the optical disc device according to the first embodiment of the present invention.

3A is a diagram showing four regions of a cross section between the optical disk and the hologram of a light beam reflected from the optical disk according to the first embodiment of the present invention, and FIG. 3B is a plan view of the hologram element. .

FIG. 4 is a plan view of a light receiving element substrate according to the first embodiment of the present invention.

FIG. 5 is a main part plan view showing four light receiving regions and a region of spot light to be irradiated according to the first embodiment of the present invention.

FIG. 6A is a diagram illustrating a configuration of a light receiving region according to the first embodiment of the present invention, and FIG. 6B is a diagram illustrating a configuration of a light receiving region in the prior art.

FIG. 7 is a diagram illustrating detection of a focus error signal according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating detection of a tracking error signal according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating detection of a tracking error signal according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating detection of a tracking error signal according to a third embodiment of the present invention.

FIG. 11 is a diagram illustrating detection of a tracking error signal according to a fourth embodiment of the present invention.

FIG. 12 is a schematic perspective view of an optical pickup according to the prior art.

FIG. 13 is a plan view of a hologram element according to the prior art.

FIG. 14 is a plan view of a light receiving element substrate according to the prior art.

FIG. 15 is a diagram showing a divided region of a spot light according to the prior art.

FIG. 16 is a diagram showing an irradiation state of each light receiving region according to the prior art.

FIG. 17 is a diagram illustrating detection of a tracking error signal according to the prior art.

FIG. 18 is a diagram illustrating detection of a focus error signal according to the related art.

[Explanation of symbols]

 Reference Signs List 2 light receiving element substrate 6 optical disk (information recording medium) 8 hologram element 9a first hologram pair area 9b second hologram pair area 10 first light reception area 11 second light reception area 12 third light reception area 13 fourth light reception area 14 housing 15 Error detecting means 19 Optical device 20 Reflected light 21a, 21b ± 1st-order diffracted light 22a, 22b ± 1st-order diffracted light 23 Spot light C Optical axis T Tangential direction (direction parallel to track) R Radial direction (perpendicular to tracking direction) + Rα Boundary direction -Rα Boundary direction O Convergence point Ea Central divided area Eb, Ec Edge divided area

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 CA01 CA05 CA08 CA15 CA17 CA20 5D118 AA14 BA01 BB08 BF02 CA24 CB03 CB05 CD02 CD03 CF04 CF06 DA20 DB02 DB04 DB07 DB18 DB27 5D119 AA11 BA01 BB13 CA15 DA05 EA02 EA03 KA04 JA15 KA03 JA15 KA27 KA43 LB06

Claims (5)

[Claims] 1. An optical pickup for irradiating an information recording medium with light and reading information using reflected light from the information recording medium, wherein the optical pickup is arranged on an optical path of the reflected light, and substantially aligns an optical axis of the reflected light. Are divided into at least four areas by two straight lines, a direction substantially parallel to the track of the information recording medium and a direction substantially orthogonal to the track, and areas arranged diagonally of the four areas are defined as the same hologram curve group. The first combining the two parts of
A hologram pair region and a second hologram pair region in which two different hologram curve groups different from each other are combined are configured as a second hologram pair region, and the first hologram pair region and the second hologram pair region are each diffracted by the reflected light. A hologram element configured to diffract light in directions different from each other and to add a convergent or divergent lens action to each of the diffracted lights, and a hologram element from the first hologram pair region of the hologram element. A light receiving element substrate having first and second light receiving areas for receiving first order diffracted light, and third and fourth light receiving areas for receiving ± first order diffracted light from the second hologram pair area, respectively, on the same plane; An optical pickup, comprising: 2. The optical pickup according to claim 1, wherein the light receiving element substrate is configured such that each of the centers of the first to fourth light receiving areas and the convergence point of the reflected light from the information recording medium are the hologram element. The first light receiving area and the second light receiving area, and the third light receiving area and the fourth light receiving area, which are arranged at optically substantially equal distances from the center of the light receiving area and are opposed to each other with the optical axis interposed therebetween. An optical pickup characterized in that a direction connecting the centers of the regions is defined as a boundary direction, and the region is divided into three parts along the boundary direction into a central divided region and both outer end divided regions. 3. An optical disc apparatus for irradiating light onto an information recording medium and reading information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, and substantially aligns an optical axis of the reflected light. Are divided into at least four areas by two straight lines, a direction substantially parallel to the track of the information recording medium and a direction substantially orthogonal to the track, and areas arranged diagonally of the four areas are defined as the same hologram curve group. The first combining the two parts of
A hologram pair region and a second hologram pair region in which two different hologram curve groups different from each other are combined are configured as a second hologram pair region, and the first hologram pair region and the second hologram pair region are each diffracted by the reflected light. A hologram element configured to diffract light in directions different from each other and to add a convergent or divergent lens action to each of the diffracted lights, and a hologram element from the first hologram pair region of the hologram element. The first and second light receiving areas for receiving first-order diffracted light, and the third and fourth light-receiving areas for receiving ± first-order diffracted light from the second hologram pair area, respectively, are on the same plane. When the respective centers of the fourth light receiving area and the convergence point of the reflected light from the information recording medium are all located at optically substantially equal distances from the center of the hologram element, A direction connecting the centers of the first light receiving region and the second light receiving region and the third light receiving region and the fourth light receiving region which are opposed to each other with the optical axis interposed therebetween is defined as a boundary direction. A light receiving element substrate divided into three parts along a direction into a central divided area and end divided areas on both outer sides thereof; and a photoelectric signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate. The difference level between the conversion signal and the sum of the photoelectric conversion signals from both outer end light receiving regions is obtained, and based on this, a focus error signal of a so-called spot size method is obtained, and the first light receiving region and the second light receiving region are obtained. Adding all the photoelectric conversion signals from the light receiving area, and
Error signal detecting means for adding all the photoelectric conversion signals from the light receiving area and the fourth light receiving area and simultaneously obtaining a so-called two-element phase difference tracking error signal from the outputs of these two systems. Optical disk device. 4. An optical disc apparatus for irradiating light onto an information recording medium and reading information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, and substantially aligns an optical axis of the reflected light. Are divided into at least four areas by two straight lines, a direction substantially parallel to the track of the information recording medium and a direction substantially orthogonal to the track, and areas arranged diagonally of the four areas are defined as the same hologram curve group. The first combining the two parts of
A hologram pair region and a second hologram pair region in which two different hologram curve groups different from each other are combined are configured as a second hologram pair region, and the first hologram pair region and the second hologram pair region are each diffracted by the reflected light. A hologram element configured to diffract light in directions different from each other and to add a convergent or divergent lens action to each of the diffracted lights, and a hologram element from the first hologram pair region of the hologram element. The first and second light receiving areas for receiving first-order diffracted light, and the third and fourth light-receiving areas for receiving ± first-order diffracted light from the second hologram pair area, respectively, are on the same plane. When the respective centers of the fourth light receiving area and the convergence point of the reflected light from the information recording medium are all located at optically substantially equal distances from the center of the hologram element, A direction connecting the centers of the first light receiving region and the second light receiving region and the third light receiving region and the fourth light receiving region which are opposed to each other with the optical axis interposed therebetween is defined as a boundary direction. A light receiving element substrate divided into three parts along a direction into a central divided area and end divided areas on both outer sides thereof; and a photoelectric signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate. The difference level between the conversion signal and the sum of the photoelectric conversion signals from both outer end light receiving regions is obtained, and based on this, a focus error signal of a so-called spot size method is obtained, and the first light receiving region and the second light receiving region are obtained. The photoelectric conversion signals from the corresponding end divided regions with the light receiving region are added to obtain outputs of two systems, and the photoelectric conversion from the corresponding end divided regions of the third light receiving region and the fourth light receiving region is performed. Each signal Adding to obtain the output of the two systems, the optical disk apparatus characterized by comprising a these 4 lines simultaneously obtain error signal detection means a tracking error signal of the so-called four-element phase difference method from the output of. 5. An optical disc device for irradiating light onto an information recording medium and reading information using reflected light from the information recording medium, wherein the optical disc apparatus is disposed on an optical path of the reflected light, and substantially aligns the optical axis of the reflected light. Are divided into at least four areas by two straight lines, a direction substantially parallel to the track of the information recording medium and a direction substantially orthogonal to the track, and areas arranged diagonally of the four areas are defined as the same hologram curve group. The first combining the two parts of
A hologram pair region and a second hologram pair region in which two different hologram curve groups different from each other are combined are configured as a second hologram pair region, and the first hologram pair region and the second hologram pair region are each diffracted by the reflected light. A hologram element configured to diffract light in directions different from each other and to add a convergent or divergent lens action to each of the diffracted lights, and a hologram element from the first hologram pair region of the hologram element. The first and second light receiving areas for receiving first-order diffracted light, and the third and fourth light-receiving areas for receiving ± first-order diffracted light from the second hologram pair area, respectively, are on the same plane. When the respective centers of the fourth light receiving area and the convergence point of the reflected light from the information recording medium are all located at optically substantially equal distances from the center of the hologram element, A direction connecting the centers of the first light receiving region and the second light receiving region and the third light receiving region and the fourth light receiving region which are opposed to each other with the optical axis interposed therebetween is defined as a boundary direction. A light receiving element substrate divided into three parts along a direction into a central divided area and end divided areas on both outer sides thereof; and a photoelectric signal from the central divided area of the first to fourth light receiving areas of the light receiving element substrate. The difference level between the conversion signal and the sum of the photoelectric conversion signals from both outer end light receiving regions is obtained, and based on this, a focus error signal of a so-called spot size method is obtained, and the first light receiving region and the second light receiving region are obtained. The photoelectric conversion signals from the end divided regions corresponding to the light receiving region are added, and the photoelectric conversion signals from the central divided regions of the first light receiving region and the second light receiving region are added to the respective added values. Add more To obtain the outputs of two systems, add the photoelectric conversion signals from the corresponding end divided regions of the third light receiving region and the fourth light receiving region, and add the third light receiving region to each of the added values. An error signal that further adds each photoelectric conversion signal from the central divided area with the fourth light receiving area to obtain two outputs, and simultaneously obtains a so-called four-element phase difference tracking error signal from these four outputs. An optical disk device comprising: a detection unit.